1. Field of the Invention
The present invention relates to a new process for the decontamination by radiation of a product, in particular a packaging containing medical devices.
2. Description of the Related Art
The conditions of sterility in which certain stages of the handling or transportation of items or instruments intended for medical use are to be performed are extremely strict, particularly in the pharmaceutical industry. It is therefore extremely important to produce packaging compatible with such requirements.
In the present application, the expression “radiation screen” is to be understood as being a screen capable of reflecting or absorbing substantially all the kinetic energy of the electrons from an electron beam, and therefore of preventing these electrons from passing through the said screen.
In the present application, the expression “semi-permeable radiation screen” is to be understood as being a screen capable of partially reflecting or absorbing the kinetic energy of the electrons from an electron beam, and therefore of allowing only a restricted percentage of these electrons to pass through the screen.
In the present application, the expression “selectively impervious material” is to be understood as meaning that the material is designed, in terms of structure, to control any exchange between the inside of the packaging and its external environment. This means, among other things, that the packaging is impervious to contamination by micro-organisms, bacteria and/or a biologically active material likely to come into contact with the packaging while it is being handled, while at the same time remaining permeable to a sterilization or decontamination gas, for example of the ETO (ethylene oxide) type.
Packagings for items that are or may be sterilized by a sterilization gas are known. In the case of medical items such as syringes, these packaging usually comprise a tub sealed with a cover sheet made of a selectively impervious material. An example of such a packaging is shown on FIGS. 1 and 2. FIG. 1 is a cross section view of a product which is a packaging 1 comprising a tub 2 and a cover sheet 3, usually made of a selectively impervious material, the cover sheet 3 being sealed to the tub 2 so as to seal the tub 2 imperviously. The tub 2 comprises a plurality of medical items under the form of syringes bodies 4. In the example shown, the syringes bodies 4 are received in holes designed on a plate placed inside the tub 2 and bearing on a rim provided on the inner wall of the tub 2.
As appears clearly from FIG. 2, which is a top view of the packaging 1 of FIG. 1, the cover sheet 3 defines a central area 5, located more or less above the syringe bodies 4, which are shown in dashes, and a peripheral outline 6 surrounding this central area 5. The peripheral outline 6 corresponds more or less to the sealing portion of the cover sheet 3 on the tub 2.
Usually, in order to proceed with the sterilization of the items 4 contained in such a packaging 1, a sterilization gas, for example of the ethylene oxide type, enters the tub 2 through the cover sheet 3 of selectively impervious material. The tub 2 containing the sterilized items 4 is then placed in a protective bag so that the tub 2 can be transported. To proceed with the subsequent handling step, for example the filling of the syringe bodies 4, the protective bag needs to be opened. The packaging 1, which may then be contaminated, needs to be decontaminated before it is taken, for example, into a sterile room.
Such decontamination can be achieved using multidirectional irradiation by an electron beam developing enough energy that when it has passed through the cover sheet, it delivers a dose of irradiation of, for example, 25 kGy. This means that it can be taken that the selectively impervious material has been decontaminated throughout its thickness, particularly at the sealing portion located at the peripheral outline 6 of the cover sheet 3 at the interface between the tub 2 and the material. Indeed, it is very important that the peripheral outline 6 of the cover sheet 3, the downside 6a (see FIG. 1) of which is not in contact with the sealed atmosphere of the inside of the tub 2, unlike the downside 5a of the central area 5 of the cover sheet 3, be totally decontaminated. As far as the rest of the tub 2 is concerned, namely the bottom and lateral walls of said tub 2, the combination of the density and thickness of said tub 2 is such that it stops these electrons.
This type of decontamination is not, however, suitable for every type of product transported in the packaging. This is because the electron beam passing through the sheet of selectively impervious material carries the risk of altering or adversely affecting the material of which the syringes or products placed in the tub are made, for example glass. The electron beam can also generate ozone from the oxygen in the air contained in the tub. The generated ozone carries the risk of polluting the atmosphere and of adversely affecting the active products used to fill the syringes and/or, for example, the rubber components present in the tub such as the caps on the needles mounted on the syringes.
There is, therefore, a need for a process of sterilization of a product, in particular of a packaging containing medical devices as described above, that would allow the efficient decontamination of the peripheral outline of the product while preserving the integrity of the items stored in the product or the internal part of the product, regardless of the shape of the product.